Diff source dump and previous version dump for Cross-Version ABI Check

Created a function to determine the current finalization stage by
environment variable and the existence of a version folder
prebuilt/abi-dumps/<lib_type>/<platform_sdk_version>/.
Assign the corresponding prevVersion with the current stage and generate
mk commands to diff source and previous dump to
{fileName}.{prevVersion}.abidiff with diff flag --allow-extension and
--advice-only
The test is verified in all stages. lsdumps should be prepared in
advance.
For stage 1: current/ and PLATFORM_SDK_VERSION/
For stage 2: current/ and {PLATFORM_SDK_VERSION-1}/
For stage 3: PLATFORM_SDK_VERSION/ and {PLATFORM_SDK_VERSION-1}/
The definition of stages could be found at
"go/cross-version-abi-check#bookmark=id.vpflkul2z968"

Test: make libbinder_ndk
Bug: 238387082
Change-Id: Ic29456113a541650c75fa38c5c4f2d6d2e76a877
diff --git a/cc/androidmk.go b/cc/androidmk.go
index ff5ba45..47fb919 100644
--- a/cc/androidmk.go
+++ b/cc/androidmk.go
@@ -226,17 +226,27 @@
 	}
 }
 
-func (library *libraryDecorator) androidMkEntriesWriteAdditionalDependenciesForSourceAbiDiff(entries *android.AndroidMkEntries) {
-	if library.sAbiDiff.Valid() && !library.static() {
-		entries.AddStrings("LOCAL_ADDITIONAL_DEPENDENCIES", library.sAbiDiff.String())
+func (library *libraryDecorator) getAbiDiffsForAndroidMkDeps() []string {
+	if library.static() {
+		return nil
 	}
+	var abiDiffs []string
+	if library.sAbiDiff.Valid() {
+		abiDiffs = append(abiDiffs, library.sAbiDiff.String())
+	}
+	if library.prevSAbiDiff.Valid() {
+		abiDiffs = append(abiDiffs, library.prevSAbiDiff.String())
+	}
+	return abiDiffs
+}
+
+func (library *libraryDecorator) androidMkEntriesWriteAdditionalDependenciesForSourceAbiDiff(entries *android.AndroidMkEntries) {
+	entries.AddStrings("LOCAL_ADDITIONAL_DEPENDENCIES", library.getAbiDiffsForAndroidMkDeps()...)
 }
 
 // TODO(ccross): remove this once apex/androidmk.go is converted to AndroidMkEntries
 func (library *libraryDecorator) androidMkWriteAdditionalDependenciesForSourceAbiDiff(w io.Writer) {
-	if library.sAbiDiff.Valid() && !library.static() {
-		fmt.Fprintln(w, "LOCAL_ADDITIONAL_DEPENDENCIES +=", library.sAbiDiff.String())
-	}
+	fmt.Fprintln(w, "LOCAL_ADDITIONAL_DEPENDENCIES +=", strings.Join(library.getAbiDiffsForAndroidMkDeps(), " "))
 }
 
 func (library *libraryDecorator) AndroidMkEntries(ctx AndroidMkContext, entries *android.AndroidMkEntries) {